The long-term goal of this project is to improve our understanding of the function of the cerebral cortex. This is being done by performing correlative anatomical and physiological studies on the visual cortex of the cat. The major aim of the proposed experiments is to delineate the function of the pathway running via the corpus callosum that connects the visual cortex in the left and right hemispheres. The left visual cortex carries a representation of the right half of the field of view, and vice versa. A narrow median strip along the vertical meridian is doubly represented. It is this strip which gives and receives the bulk of the callosal connections. In some general sense, then, the callosal pathway knits up the two half-fields and permits a seamless view of the world. The proposed study is intended to provide a more detailed picture of this operation by means of the following sets of experiments: a) the anatomical wiring will be studied by axon transport methods at a light- and electron-microscopic level. b) the nature of the signals being transmitted between the hemispheres will be studied by recording the electrical activity of single fibers in the corpus callosum. c) the contribution of the callosal pathway to the functional properties of visual cortical neurons will be studied by recording from these neurons during reversible inactivation (cooling) of the opposite visual cortex. In studying the role of the corpus callosum particular attention will be paid to its involvement in stereoscopy and other visual functions that require interactions across a considerable extent of visual space. It is hoped to determine to what extent callosal connections are functionally equivalent to local cortico-cortical connections within one hemisphere.